In 3GPP (3rd Generation Partnership Project), which is a project aiming to standardize a mobile communication system, a technology for selecting a selection target cell used as a serving cell from among a plurality of cells operated at different frequencies is proposed (for example, see Non Patent Literature 1).
Specifically, a user terminal measures, if a start condition is satisfied, a quality of a neighboring cell adjacent to a current serving cell, and selects, from cells that satisfy a selection condition, a selection target cell used as a serving cell.